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Key Points:

The National Party has dropped its opposition to the Kyoto protocol on climate change and is "looking at" a 50 per cent cut in greenhouse gas emissions by 2050. Quite a change of climate in a party which a year ago still herded with the sceptics.

John Key will spell out his thinking this coming weekend. But the new breeze is already blowing through the party.

Former president Geoff Thompson delivered a decidedly greenish briefing to its lower North Island conference on Saturday. His text had been cleared as consistent with Key's upcoming speech. No one, not even a farmer, challenged him from the floor.

The word now is "convergence" towards Labour on emissions trading. But don't tack that on to last week's smacking accord and expect consensus. The climate change repositioning is essentially a flanking action, blue-rinsed to set off Labour's watermelon hue.

The leadership has focused on the mood shift which has generated international consumer, commercial and political threats to this country's trade and business and changed the business mood here.

One senior National MP says: "Politicians are struggling to stay up. Business is pushing past them."

Thompson told the conference: "It's about taking a realistic attitude to the management of risk," and likened it to insuring your house against the (unlikely) possibility of fire. "We will be judged as a member of the international community and as exporters on our response."

Then Thompson quoted the British Treasury report by Nicholas Stern as making a "compelling case about the catastrophic effects of climate change" and Stern's economic calculation that "the long-term cost of inaction is likely to far outweigh the short-term cost of action".

Hence it would be "irresponsible" just to "adapt" because that ignores the possibility of irreversible change. Irresponsible to whom? To children and grandchildren. This is Key National, aimed at liberal, centrist, notably female, voters.

Thompson went on to promote the sort of numerical target Helen Clark and David Parker (and Key) have so far avoided: "National is looking at a 50 per cent reduction [in greenhouse gas emissions] by 2050."

And that implies: "We must spend heavily now to reduce carbon emissions and promote carbon sinks."

That is a bold target: half this country's emissions are methane from animals and there is no known way to significantly reduce that. So Thomson wants "very intensive" research.

Easier said than done. Former National minister and OECD sustainability guru Simon Upton says there are only 38 specialist animal methane scientists worldwide, 25 of them here.

Key is unlikely to go as far as Thompson, endorsing Stern and setting a target. But he will back emissions trading.

The Cabinet has, too, with a policy of "all sectors in, all gases in, no exemptions".

National agrees. Both back the Stock Exchange plan for a trading platform. There is "convergence" to that point.

But there are important differences over how much to supplement the market with regulation. National much prefers markets and financial instruments.

Neither party has yet said how initial emission allowances should be allocated, or specified the initial cap. Without a cap on emissions the incentive to trade is limited. Parker is to announce some emission trading details today.

The Government is filling in some of the other blanks. Clayton Cosgrove's energy efficiency measures for buildings last week were significant and timely. A big engineering services firm says developers are now demanding efficiency features in building designs.

Parker is due to produce legislation by September. He has to develop standards for measuring emissions for the trading regime and marry it up with his energy strategy. This is mind-stretching, complex stuff.

Meanwhile, there is a Budget next week on which the Government is pinning much hope. Expect lofty climate change rhetoric. Six months ago that might have got the jump on National. Now the picture is much murkier.

* Some people misread my column last week as saying those who opposed homosexual law reform etc were not decent people. Not so. The context made clear that the decent people I was referring to are those who might sometimes inconsequentially smack their children.